Thermal alarm



(No Model.)

H. F. MAXIM.

' THERMAL ALARM.

Patented June 26, 1894.

UNITED STATES PATE T LQO FICE.

HOSEA F.- MAXIM, OF NORFOLK, VIRGINIA.

THERMAL ALARM.

SPECIFICATION forming part of Letters Patent No. 522,022, dated June 26, 1894,

Applioationfiled August 31,1893. semi No. l8 76- (No model-J simple compact device which can be utilized.

to indicate visibly or audibly, preferably the latter, when the heat in an apartment reaches either or both of atleast two predetermined points. 1

In hotels, factories, large business and other buildings, it is desirable to have means which will operate automatically to indicate, first the instant at which a degree of heat is at tained in any of several apartments, which degree is within the safety limit, but is undesirable from the standpoint of economy of fuel, and second, a stillhigher degree at or beyond the limit of danger of-fire.

Several forms of apparatus have been devised involving the presence of the'mer'cury bulbs and tubes, such as are commonly used in making thermometers.

One of the objects of the present invention is to dispense with mercury and the fragile and expensive vessels or receptacles used for holding it, and to provide adevice which shall have a few, simply constructed andvreliably operating parts adapted to be primarily actuated by the mere expansion or contraction of solid materials, and to avoid the necessity of the ordinary thermometer fluids Figure 1 is a diagrammatic view of an apparatus embodying my invention. Fig. 2 is a face view of the thermostat and adjacent parts. Fig. 3 is an edge view of the same. Fig. 4 shows a side view of the thermostat bar and adjacent parts enlarged; and Fig. 5 shows the same in plan.

In the drawings, A, A, indicate apartments and A an office or central apartment in a building. The apartment A, and the office A are connected by one or more electric'circuits B, B, B with a battery, or batteries at any suitable place, as shown at B The apparatus in eachapartment comprises the following: 0 represents as awhole a mechanical thermostat,-thatis.to say one composed of parts of solid material, one or more of which are in whole or in part movable under a variation .in temperature. cates as a whole an electro-magnetic bell, whose parts and relation will be more fully described. Preferably the thermostat and the bell with attachments are all supported .upon a small common base or bed piece N of D indisuitable material as wood, by which they .can

be readily attached to and detached from any. desired support. There are a vast number of electro-magnetic bells now upon the market or in 'use and one of the purposes of the prescut invention is to provide a simple thermal alarm which can be applied directly to the said bells. One of these is shown in the drawings,'-the' onlyparts'sup'plemental thereto beingthe thermostat]- and two contacts. The thermostat, as shown, comprises the readily ejxpans'ible bar 0'. It is secured at c to the rnetalsdifferingas-to their expansibility, such as b'rassfand' steel.

0 is an index consisting of a needle or fin- 'backplate and is formed preferably of two er ivoted at c, and having its end arranged g P to move along a dial 0 having characters indicating' degrees of temperature. The arm C is connected by a finger c with the index finger 0 there being an aperture or slot 0 in the heel of the latter to receive said finger 0 the point of engagement being comparaa tively close to the pivot c. When-the arm 0 swings in either direction, as it does when subjected to variations in temperature, it causes ''the pointer O to move correspondingly over the index or scale. To adjust or set the pointer to any predetermined position late the length of the are over which the pointer should normally move, by variation of temperature of a given number of degrees,

I provide such an adjustment of the parts that the arm 0 can engage the pointer 0 at one or another of several points in its heel, that is nearer to or farther fromthe pivot o. This can be accomplished by slotting arm 0 as at 0 so that it can be moved bodily to change the position of the finger a To provide for a still more delicate adjustment of the pointer, for any desired purpose, I make the finger o movablerelatively to arm 0, it,

I provide adjusting screws 0 And to regu- V as shown, being threaded and having jam nuts 0 for clamping it in either of several positions. The terminals of the aforesaid circuit B, B, are secured to the binding posts F, F. From post F wire f runs to pivot screw 0 and arm 0', and when current enters at said post, it will pass through said wire, screw and arm to pointer 0 If the pointer be moved far enough, it will strike the contact G. From this contact a wire 9 extends to a supplemental post H, and from this a third main wire B extendsto the office or central apartment A where it is connected to one of the terminals of an alarm apparatus I, the wire B being connected to the other terminal. It will be seen that when pointer C touches the contact G, circuit is closed through 13,13 and that the alarm I is sounded the current passing from wire 13 through binding post F, wire f, screw 0 bar 0', finger c pointer, 0 contact G, wire g, and binding post 1-1 to wire B thence to the office where the bell and the battery are located. But the contact G is not rigid in position. It can yield sufiiciently to provide for forming electric connection between pointer 0 and a second contact or terminal J. The latter is con nected by wires j, with the metallic frame of the magnet, and the post F of wire B is connected by wire f with the coils of magnet D tact J wire 0st Z, screw 1 s rin L, arma-K ture L, frame K, wire (1', armature coils, wire f and post F to wire B and the battery, thereby intermittingly energizing the bell magnet, and sounding the alarm. nd when the apparatus is arranged as shown the pointer O can be in contact with both the terminals G and J simultaneously and consequently both the alarms (that at I in the oflice and that at D in the apartment) will sound.

The manner of using the apparatus is as follows: The index or scale at C is constructed so that the contact G shall lie at the zero point. Then by means of the adjusting device, the arm 0 is moved so as to bring the pointer to that point on the scale where is indicated the degree of temperature which is to be the limit for ordinary heating purposes. For instance if it is desired to maintain in a given apartment a temperature of about Fahrenheit and to have an alarm sounded if it should rise to Fahrenheit the parts of the above described thermostat are so set that the pointer lies at 10 from zero. And if at the same time it is desired to have another alarm sounded, in the apartment itself, in case the temperature should rise to a considerably higher degree, say the contact J is adjusted so as to lie at a point 20 beyond the contact G. After these adjustments have been made the following results will occur. If the temperature should rise to 80,

the arm 0' will be affected sufficiently to move the pointer to terminal G, and thereupon the above described circuit through B and B will be closed, and the ofice alarm will sound. And thus an alarm is given in pursuance of which steps can be taken to reduce the heat of the stove, furnace, steam pipes, water pipes, or other meansused for normally heating the apartment. But if an exceedingly high heat should be produced, as for instance by the breaking out of a fire, the pointer will speedily reach contact G and also the contact J, whereupon the alarm circuits will be closed, not only through E and B to hell at I, but also through B and B to the apartment alarm D. i I

What I claim is- 1. In a thermal alarm the combination of the electro -magnetic alarm D, the electromagnetic alarm I remote from said alarm D, a thermostat bar, a contact G, a contact J and two electric circuits, one circuit comprising said alarm I, said thermostat bar and said contact G, and the otherof said circuits comby means of the expansible bar 0 substantially as described.

3. The combination of the electro-magnetic alarm D, the thermostat 0, having an expansible bar or arm, the contact movable by said arm, the movable contact G, in the path of the aforesaid contact and adapted to be moved thereby, and the stationary but adjustable contact J, substantially as described.

4:. The combination of the electro-magnetic alarm D, the thermostat having an expansible bar C, a stationary contact, and an independently mounted contact interposed between said bar and said stationary contact and adapted to be moved by said bar into engagement with said stationary contact, substantially as set forth.

5. lhe combination of the thermostat having the bar 0, the indexhaving a zero point intermediate of its ends, and subdivisions marked on either side thereof, a movable contact lying normally at said zero point, a contact on one side thereof, and apointer or contact on the outer side thereof connected to said bar 0, the last two said contacts being adjustable toward and from the said zero point on said index, substantially as and for contact with. said contact G, the expansible thermostat bar 0, and an adjustable connection between said bar and said pointer 0 to regulate the movement of the latter, substantially as described.

7. The combination of the electro-magnetic alarm D, the contact G, the pivoted pointer or contact 0 the longitudinally adjustable thermostat bar 0, and the electric circuit connected to said bar, said pointer and to said contact G, substantially as described. H

8. The combination of the base piece or support N, the expansible thermostat bar 0' secured thereto, the vibrating contact 0 the contact G, the contact J, the electro-magnetic alarm I), the binding posts or connections F,

F and H, the electric circuit connecting said 9. The combination with the index, the pivoted pointer, the thermostat bar connected at its free end to, and actuating said pointer, and an adjustable connection between said bar and said pointer, whereby said pointer may be rendered more sensitive to delicate variations in temperature, substantially as set forth.

10. The combination of the index, the pivoted pointer having a slotted heel, the thermostat bar actuating said pointer, and a bar adjustable on said thermostat bar, and having a projection lying in said slot, substantially as and for the purposes set forth.

In testimony whereof I affix my signature in presence of two witnesses.

HOSEA F. MAXIM. Witnesses:

M. N. JENKINS, E. E. FUQUA. 

